Catalytic inhibition of human DNA topoisomerase IIalpha by hypericin, a naphthodianthrone from St. John's wort (Hypericum perforatum).

St. John's wort (Hypericum perforatum) is the most widely used herbal medicine for the treatment of depression. However, concerns have arisen about the potential of its interaction with other drugs due to the induction of cytochrome P450 isozymes 1A2 and 3A4 by the components hypericin and hyperforin, respectively. Structurally similar natural products are often employed as antitumor agents due to their action as inhibitors of DNA topoisomerases, nuclear enzymes that modify DNA during cellular proliferation. Preliminary findings that hypericin inhibited the DNA relaxation activity of topoisomerase IIalpha (topo II; EC 5.99.1.3) led us to investigate the mechanism of enzyme inhibition. Rather than stabilizing the enzyme in covalent complexes with DNA (cleavage complexes), hypericin inhibited the enzyme prior to DNA cleavage. In vitro assays indicate that hypericin is a potent antagonist of cleavage complex stabilization by the chemotherapeutics etoposide and amsacrine. This antagonism appears to be due to the ability of hypericin to intercalate or distort DNA structure, thereby precluding topo II binding and/or DNA cleavage. Supporting its non-DNA damaging, catalytic inhibition of topo II, hypericin was shown to be equitoxic to both wild-type and amsacrine-resistant HL-60 leukemia cell lines. Moreover, hypericin was incapable of stimulating DNA damage-responsive gene promoters that are activated by etoposide. As with the in vitro topo II assay, antagonism of DNA damage stimulated by 30 microM etoposide was evident in leukemia cells pretreated with 5 microM hypericin. Since many cancer patients experience clinical depression and concomitantly self-medicate with herbal remedies, extracts of St. John's wort should be investigated further for their potential to antagonize topo II-directed chemotherapy regimens.

Detection of Clavibacter michiganensis subsp. sepedonicus by DNA amplification.

Control of bacterial ring rot ultimately depends on the accurate and sensitive detection of C. michiganensis subsp. sepedonicus in infected potato tissues and tubers. Polymerase chain reaction (PCR) based detection of C. michiganensis subsp. sepedonicus appears to have the potential to circumvent many of the problems currently associated with detection of this phytopathogen. PCR reactions using primers specific to C. michiganensis subsp. sepedonicus and genomic DNAs from related strains, including phytopathogens, did not produce any amplification products. C. michiganensis subsp. sepedonicus was detectable from a mixture of potato and bacterial DNA by amplification of a DNA sequence specific to C. michiganensis subsp. sepedonicus. Detection by DNA amplification allowed direct processing of plant tissue samples, and circumvented the need for prior isolation of the suspected phytopathogen.

Histological evaluation of the effect of transseptal fibre resection on the rate of physiological migration of rat molar teeth.

Twenty-seven female Sprague-Dawley rats were given lead acetate as a vital stain, and rates of alveolar bone formation, representative of drift, were measured histologically. Teeth around which the transseptal fibre system had been destroyed drifted less quickly on both functioning (p less than 0.01) and non-functioning (p less than 0.001) sides than those with intact transseptal fibres. Both horizontal and vertical components of physiological drift were equally affected by destruction of the transseptal fibre system. It was felt that the transseptal fibres probably exerted their primary effect on the tooth, with bone remodelling around the drifting tooth being affected secondarily.

A study in animal ethics in New Brunswick.

Society uses animals in ever-increasing numbers and ways, providing ethical challenges. Decisions about animal use are guided by the social consensus ethic towards animals. Because there is no clear social consensus ethic, these decisions are difficult. Society's ethic is changing and a "new ethic" towards animals is emerging. This study addressed the need to better understand society's ethics towards animals. Qualitative research methodology (focus groups) was used to study 7 different animal-interest groups. Qualitative data analysis was computer-aided. The group ethical position towards animals of its own group interest was determined for each group. The animal welfare, companion animal, and veterinary groups took Rollin's Position, a position based on both the Utilitarian and the Rights Principles; the farmer and trapper groups the Utilitarian/Land Ethic position, a dual position based on actions producing the greatest amount of pleasure and the least amount of pain for the greatest number, and preserving the integrity, stability, and beauty of the biotic community; the hunter group the Utilitarian/Judeo-Christian position, a dual position based on actions producing the greatest amount of pleasure and the least amount of pain for the greatest number, and having dominion over animals; and the naturalist group took Rollin's Position/Land Ethic. All these groups perceived medium to extreme ethical responsibility towards animals of their own group's interest that are used by others. The study showed that the predicted "new ethic" towards animals is in New Brunswick society and it is Rollin's Position.

Cephalometric appraisal of posttreatment vertical changes in adult orthodontic patients.

The purpose of this study was to evaluate vertical facial changes in adult orthodontic patients and to evaluate the stability of these changes. Thirty-three patients (8 males and 25 females) were examined. The patients had been treated with full fixed edgewise appliance mechanics and exhibited at least 1.0 degrees of clockwise rotation of the mandible during treatment. Mandibular rotation was determined by the angular change in the Y-axis to the Frankfort plane. Twelve angular and 14 linear skeletal and dental measurements and 3 skeletal ratios were derived from pretreatment (T1), posttreatment (T2), and postretention (T3) cephalometric radiographs. Paired t tests were used to compare vertical changes that occurred as a result of orthodontic treatment and their stability or relapse tendency during the retention and postretention periods. Twenty-five percent (P <.001) of the opening rotation of the mandible recovered during the posttreatment period, resulting in a significant overall rotation that was maintained. Both treatment and posttreatment changes in the Y-axis angle showed a high correlation with the horizontal position of pogonion (r = -0.797 and -0.889, respectively). Only overjet showed a low correlation between treatment changes and posttreatment changes in the Y-axis angle. Stepwise regression analysis of pretreatment variables and treatment changes failed to predict the behavior of the Y-axis angle change.

Comparison of Roth appliance and standard edgewise appliance treatment results.

A retrospective comparison of Roth appliance and standard edgewise appliance treatment results was made using two indices. The first, the ideal tooth relationship index (ITRI), scored dental casts for the presence of ideal tooth contacts. The second judged posttreatment dental casts on the basis of criteria established by Andrews in his "Six Keys to Normal Occlusion." The sample consisted of 120 orthodontically treated cases completed by two practitioners who have used both the Roth and standard edgewise appliances. Thirty cases of each appliance type were collected from each practitioner. The overall posttreatment ITRI percentage scores showed no significant differences between the appliances. Practitioner differences existed for the anterior intraarch, anterior interarch, and posterior buccal interarch relationships. These differences were related to both treatment time and finishing arch wire size. The results of the Six Keys Analysis showed that the angulation and inclination of the maxillary posterior teeth were better with the Roth appliance. However, success in achieving some components of the six keys did not translate into an increased percentage of ideal tooth contacts as measured by the ITRI. Despite using the Roth appliance, experienced clinicians still found it difficult to achieve all six keys to normal occlusion.

Facial and dental arch asymmetries in Class II subdivision malocclusion.

The purpose of this investigation was to determine if any significant differences existed with regard to dental arch and facial asymmetries between persons having malocclusions with well-defined asymmetric characteristics, specifically Angle's Class II subdivision malocclusions, and persons having normal occlusions. Secondarily, it was sought to determine the nature of the differences that contributed to the asymmetric occlusal relationship of buccal segments observed in Class II subdivision malocclusions. The sample consisted of 28 subjects in each of the two groups. All possessed a full complement of permanent teeth including first molars. The average age of subjects in both groups was 17 years. Measurements primarily of a linear nature were obtained from posteroanterior and lateral cephalometric radiographs in addition to dental models. Specific measurements were summed to produce various indices of asymmetry. Variables were analyzed with multivariate discriminant analysis. A significant discrimination between the two groups resulted; variables describing asymmetry of the dentoalveolar region of the mandible appeared to be the primary contributors to the difference obtained. Asymmetry of the maxillary dentoalveolar region appeared to make a secondary contribution.

An assessment of treatment outcome in American Board of Orthodontics cases.

In a retrospective study, 90 American Board of Orthodontic (ABO) cases were evaluated for treatment outcome. Changes in occlusion, cephalometric skeletal and dental variables, soft tissue variables, and root resorption were evaluated. The occlusions of completed ABO cases were compared with 147 naturally occurring good-to-excellent occlusions from the Andrews Foundation for Education and Research, using the Ideal Tooth Relationship Index (ITRI). Cephalometric variables were evaluated in relation to an "acceptable range" based on established standards. Photographs were evaluated for lip posture at rest and at closure, and the incidence and the severity of root resorption of maxillary and mandibular teeth excluding second molars were evaluated from panoramic radiographs. After treatment, occlusions of ABO cases scored significantly higher overall and for all ITRI segments except the anterior interarch segment when compared with Andrew's sample. In all the ABO cases, ideal overjet and overbite were attained. Cephalometrically, the mandibular plane and the Y-axis angle showed no significant change as a result of treatment. However, skeletal dysplasia (ANB) and skeletal convexity (Na-A-Po) showed improvement. Dentally, the maxillary incisor position and inclination, the interincisal angle, and the lower incisor position ended within the acceptable range, whereas the lower incisors were proclined. Soft tissue variables also improved, lip balance and harmony, closure at rest, and closure without strain all improved. The nasolabial angle showed little change. Most of the root resorption was minor in nature and involved the maxillary and mandibular central and lateral incisors. In conclusion, the ABO cases were well treated and showed marked improvement in occlusion, cephalometric, and soft tissue changes, although experiencing minor iatrogenic effects.

A static occlusal analysis based on ideal interarch and intraarch relationships.

Study models were visually assessed to quantify the number of ideal tooth relationships actually present relative to the potential total. Both intraarch and interarch relationships were used to generate an ideal tooth relationship index (ITRI). Index scores were generated for the entire dentition, which could be divided into anterior, posterior, interarch, and intraarch relationships. Index scores were determined at various time intervals so the longitudinal changes could be studied. Treated orthodontic cases (n = 92) showed an initial total ITRI score of 26% that increased to 52% at the end of orthodontic treatment and continued to improve to 59% during the retention and postretention periods. Anterior segment scores were higher (64%) than posterior segment scores (44%). The intraarch relationships of the anterior segment registered the highest (75%), whereas the lingual cusp relationships of the posterior segment had the lowest scores (35%). Various types of malocclusions exhibited different ITRI scores before treatment but responded equally to treatment showing similar improvement in scores at the end of treatment and the posttreatment period.

Verification of the role of PCP 4-monooxygenase in chlorine elimination from pentachlorophenol by Flavobacterium sp. strain ATCC 39723.

The bacterial enzyme PCP 4-monooxygenase from Flavobacterium sp. strain ATCC 39723 catalyzes the oxygenolytic removal of the first chlorine from pentachlorophenol. PCP 4-monooxygenase is an FAD binding, NADPH requiring oxygenase, with similar functional domains as other bacterial flavoprotein monooxygenases specific for phenolic substrates. However, the definitive proof for the singular role of an oxygenolytic elimination of the primary chlorine from pentachlorophenol by Flavobacterium sp. has awaited the development of a genetic system whereby targeted mutagenesis via allelic exchange could be carried out with the corresponding gene from PCP 4-monooxygenase, pcpB. We report the development of a genetic system for Flavobacterium sp. strain ATCC 39723, and its application in targeted mutagenesis of the pcpB allele for elimination of PCP 4-monooxygenase activity.

A comparative study of anchorage in bioprogressive versus standard edgewise treatment in Class II correction with intermaxillary elastic force.

The primary purpose of this study was to evaluate the effectiveness of cortical anchorage, by comparing two groups of patients with Class II malocclusions that were treated successfully with Class II elastics. One group of 30 previously treated patients had a utility arch used to set up cortical anchorage in the lower arch before Class II elastic wear; the second group was treated with standard edgewise mechanics where anchorage preparation consisted of full appliances, a well-aligned mandibular arch, and a rectangular arch wire. The groups were selected according to age, sex, and the amount of Class II elastic usage. Pretreatment and posttreatment cephalometric radiographs were used to generate 32 variables. A Student's t test was used to evaluate treatment change between the groups and revealed that there were no statistically significant differences. Lower molar teeth extruded and moved mesially equally in both groups. Although cortical anchorage did not retard lower molar movement, it was no less effective in controlling molar movement with a partial appliance than the fully banded standard edgewise appliance.

Cloning, sequence analysis, and expression of the Flavobacterium pentachlorophenol-4-monooxygenase gene in Escherichia coli.

The pcpB gene of Flavobacterium sp. strain ATCC 39723 was cloned by using a degenerate primer designed from the N-terminal sequence of the purified enzyme. The nucleotide sequence of pcpB was determined and found to encode an open reading frame of 1,614 nucleotides, yielding a predicted translation product of 538 amino acids, in agreement with the estimated size of the purified protein analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The transcriptional start of pcpB was found to be 80 bp upstream of the translational start, and the transcript was found to be induced in Flavobacterium sp. strain ATCC 39723 by the presence of pentachlorophenol but to be constitutive in the Escherichia coli pcpB clone. DNA hybridizations with genomic DNAs from Arthrobacter sp. strain ATCC 33790 and Pseudomonas sp. strain SR3 revealed a similar-size 3.0-kb EcoRI fragment, whereas there was no positive hybridization with genomic DNA from Rhodococcus chlorophenolicus. Cell extracts from an E. coli pcpB overexpression strain, as well as the whole cells, were proficient in the dechlorination of pentachlorophenol to tetrachlorohydroquinone. Protein data base comparisons of the predicted translation products revealed regions of homology with other microbial monooxygenases, including phenol-2-monooxygenase and tryptophan-2-monooxygenase.

Long-term stability after orthodontic treatment: nonextraction with prolonged retention.

A sample of 22 previously treated orthodontic cases was studied to evaluate long-term stability. All cases were treated nonextraction with fixed edgewise appliances and were without retainers a minimum of 5 years. Data were obtained from study models, although 14 of the 22 cases had longitudinal cephalometric radiographs. The average retention time with a mandibular fixed lingual retainer was 8.4 years. The irregularity index pretreatment was 8.0 mm in the maxillary arch and 5.2 mm in the mandibular arch; at the end of treatment it was 0.9 mm and 1.0 mm, respectively, and at the postretention stage it was 2.0 mm and 2.4 mm, respectively. Resolution of the lower irregularity index was accomplished without incisor advancement or distal movement of the mandibular molar, however, both arches were expanded transversely. During the posttreatment stage all variables showed relapse except for the expanded maxillary canines and premolars. However, the mandibular anterior segment demonstrated relatively good alignment at the long-term stage, which may be a reflection of prolonged mandibular retention.